Devices which capture energy from the wind that include rotational means about an axis which is parallel to an array of blades are most commonly disposed perpendicular to the ground and are therefore generally referred to as “vertical windmills.” This orientation allows the wind machine to be omnidirectional with respect to the airflow, which in most places is parallel to the ground. An example of such a wind device is shown in U.S. Pat. No. 7,084,523 depicted in FIG. 1. Although the blades are different, this is a structural example of a simple fixed-wing vertical windmill similar to the invention which includes blades 2 which are supported by arms 5 that connect the blades to a central axial member 1 which supports the blades and transmits the rotational energy caused by their movement.
It is also known in the field of wind energy devices to construct blades or wings which can capture the force of the airflow in different ways. One known blade configuration is shown in U.S. Pat. No. 5,599,172 issued to McCabe, depicted herein in FIG. 2. The cross-sectional shape of this blade shows that it comprises essentially a planar face portion B and leading and trailing edges A and C at opposite ends of the face portion respectively. Attached to the trailing edge is a flange, D that cups the wind. The resulting construction is an inverted pan-shaped blade. It is theorized that this blade shape captures air rather than letting it pass freely through the apparatus. This pan-shaped blade has two effects. First, it causes aerodynamic lift. Secondly, the adjacent blade can enhance the lift. This device operates best with the airfoils at significantly shallower angles than windmills using standard airfoils. Thus, the device will not continuously accelerate and burn up because the relative wind change due to rotation reduces lift, acting as a braking action as the angle of attack approaches the zero lift range. In operation, this means that the device collects as much force as possible even though it is going slower rather than faster, as in the prior art. For example, in a 60 to 65 mph wind, the maximum speed would be approximately 100 revolutions per minute (rpm).